Interspinal stabilization system

ABSTRACT

An interspinous stabilization system comprising three elements and characterized in that two of its elements, called spinous anchoring parts ( 1, 3 ), are fastened to the superior and inferior spinous processes, and the third element, called an intermediate part ( 2 ), is interposed between the other two in order to ensure distraction of the interspinous space and movability of the device in the three spatial planes.

The present invention relates to an item of equipment intended to beimplanted at the vertebral level between the spinous processes in orderto improve intervertebral stability (by restoring tension on thecapsulo-ligamentary apparatus, enlarging the conjugation holes, andreducing pressure in the disc space and between the articular facets)and to avoid, whenever possible, arthrodesis in destabilizing andsymptomatic degenerative diseases.

The invention relates more particularly to refinements to this type ofimplant. Several models of this kind of interspinous implant presentlyexist, and despite successive improvements developed by manufacturers,none of these implants is entirely satisfactory.

Interspinous implants are generally single-piece, made either of metalor of rigid materials (PEEK, etc.) or of flexible materials(polyurethane covered with woven polyester, or flat woven polyesterrolled into a cylinder). Fastening methods are designed in such a waythat it is difficult to fasten more than one space at a time, with atightening tension that is difficult to constantly evaluate. The resultis either excessively rigid fastening that can sometimes lead toarthrodesis (which is not the objective), or insufficient fastening thatcan result in medium-term loosening, with painful conflict between theimplant and the spinous processes.

The implant according to the present invention provides an effectivesolution to the underlying problem of adapting the implant to allanatomical and physiological variations.

The implant according to the present invention comprises three elements:two rigid spinous anchoring parts that can be of variable shapes(identical or not), and one intermediate part of variable thickness andphysical consistency, allowing the installation height and elasticity tobe controlled at will. The intermediate piece fits between the spinousanchoring parts.

According to one characteristic of the invention, the interfaces betweenthe spinous anchoring parts and the intermediate part are flat orcylindrical in shape, so that upon installation they can be fastened inrotationally movable fashion while ensuring satisfactory and lastingstability.

According to another characteristic of the invention, the implant can befastened to the spinous processes by a metal device that passestransversely through the bone or by a flexible ligamentary devicelooping around the processes.

According to an advantageous provision of the invention, the shape ofthe implant and the fastening methods are designed so that two or moreadjacent spaces can be equipped if necessary.

The interspinous stabilization system according to the presentinvention, comprising three elements, is thus characterized in that twoof its elements, called spinous anchoring parts, are fastened to thesuperior and inferior spinous processes, and the third element, calledan intermediate part, is interposed between the other two to ensuredistraction of the interspinous space and movability of the device inthe three spatial planes.

According to a complementary characteristic, the spinous anchoring partspossess, on the side opposite the spinous process, orifices of variousshapes, or blocks, in which the intermediate part fits by way of thecorresponding blocks or orifices in order to ensure movability of thesystem.

According to another characteristic, the intermediate part that isintended to be interposed between the spinous anchoring parts hasdifferent shapes and heights and is equipped or not equipped withpassthroughs or blocks, and is fabricated with different types ofmaterial, to facilitate movement between the various elements of thedevice.

It may be added that the intermediate part has, for example, anelliptical shape that fits into orifices of the same shape on thespinous anchoring parts in order to provide multidirectional movementfor the device.

It may also be noted that the intermediate part is equipped withcylindrical blocks that fit into the corresponding orifices of thespinous anchoring parts.

According to another characteristic, the spinous anchoring parts areequipped with cylindrical orifices to receive the cylindrical blocks ofthe intermediate part, thus forming a rotationally movable device.

According to a variant, the spinous anchoring parts are equipped withoblong orifices to receive the cylindrical blocks of the intermediatepart, thus forming a device that is movable rotationally and inlaterally sliding fashion.

According to another variant implementation, the intermediate part isequipped with a threaded anterior orifice to facilitate grasping andassembly, and has transverse tunnels passing through that allowfastening of the system by way of a flexible ligamentary device andprovide an additional contribution to the shock-absorbing effect.

It may be added that the intermediate part is constituted by a planarsegment to allow rotation and anterior-posterior and lateraltranslation, and a spherical segment to permit anterior, posterior, andlateral tilting. The entire assembly permits movability in the threespatial planes.

Other characteristics and advantages of the invention will emerge fromthe description below with reference to the attached drawings, which areprovided only as non-limiting examples.

FIGS. 1 to 9 depict the various parts of the system according to thepresent invention.

FIGS. 1 to 3 illustrate a first embodiment called a “movable system.”

FIG. 1 is a front view of the assembled movable system.

FIG. 2 is a side view of the assembled movable system.

FIG. 3 is a perspective view of the three separated parts of the movablesystem.

FIGS. 4 to 6 illustrate a second embodiment called a “fixed system.”

FIG. 4 is a front view of the fixed system.

FIG. 5 is a side view of the fixed system.

FIG. 6 is a perspective view of the three parts of the fixed system.

FIGS. 7 to 9 illustrate a third embodiment called a “spherical system.”

FIG. 7 is a front view of the spherical system.

FIG. 8 is a perspective view of the three parts of the spherical system.

FIG. 9 is another perspective view of the three parts of the sphericalsystem.

The attached drawings illustrate the invention. A description will begiven below, with reference to FIGS. 1 to 9, of the characteristics andoperation of the “interspinous stabilization system.”

The system according to the present invention comprises three elements:two anchoring parts 1, 3, namely a superior spinous anchoring part 1, anintermediate part 2, and an inferior spinous anchoring part 3.

According to a characteristic of the invention, all the elements aremachined using metallic or nonmetallic biocompatible materials, and canbe adapted to all anatomical variations.

According to an advantageous design, spinous anchoring parts 1, 3 aremade up of a channel-shaped body 4 having a throat 7 of cylindricalsection, flared side walls 5 penetrated by two horizontally alignedorifices 6 allowing grasping and fastening using a metal device, theridges of which are rounded and blunted. Flat base 10 of spinousanchoring parts 1, 3 constitutes, for the first two embodiments, theinterface with flat surface 12 of intermediate part 2.

According to a second advantageous design, spinous anchoring parts 1, 3possess, at their base, orifices 9 of various shapes, or blocks, inwhich intermediate part 2 will fit by way of corresponding blocks 13 ororifices.

According to an advantageous design, orifices 9 of the spinous anchoringparts can have a section that is square for the fixed model (FIG. 6),circular (FIG. 3) to allow rotational movements, or oblong to allowrotational and laterally sliding movements.

Spinous anchoring parts 1, 3 possess anterior and posterior flats 8 orsegments having a median rib 11 that facilitates alignment and assembly.

According to another characteristic of the invention, intermediate part2 that is intended to be interposed between spinous anchoring parts 1, 3can be of different shapes and heights, equipped or not equipped withblocks 13 or orifices.

According to an essential characteristic of the invention, intermediatepart 2 can be equipped with cylindrical blocks 13 that fit intocylindrical orifices 9 of spinous anchoring parts 1, 3 to form arotationally movable device. When orifices 9 of spinous anchoring parts1, 3 are oblong, the device becomes movable rotationally and inlaterally sliding fashion.

The ends of blocks 13 of intermediate part 2 comprise a cutout 14 toprevent any conflict with the spinous process.

Intermediate part 2 can be parallelepipedal in shape, having flatfitting segments 17 corresponding to orifices 10 of the same shape inspinous anchoring parts 1, 3.

Intermediate part 2 can have variable mechanical characteristics inorder to provide a shock-absorbing effect if necessary.

Intermediate part 2 has horizontal transverse tunnels 15, 16 passingthrough it, allowing the system to be fastened to the spinous processesby a flexible ligamentary device, and providing an additionalcontribution to the shock-absorbing effect.

Intermediate part 2 can be equipped with a threaded anterior orifice 18to facilitate grasping and assembly.

The invention is of course not limited to the implementations describedand depicted by way of example, but also encompasses all technicalequivalents as well as combinations thereof.

FIG. 9, for example, illustrates a variant that will be called a“spherical system,” according to which coaction between intermediatepart 2 and superior spinous anchoring part 1 is effected by way of aspherical contact, by the coaction of contact surface 10 of theintermediate part and contact surface 20 of anchoring part 1, these twosurfaces being spherical and of coacting shape.

1. An interspinous stabilization system comprising three elements,wherein two of its elements, called spinous anchoring parts (1, 3), arefastened to the superior and inferior spinous processes, and the thirdelement, called an intermediate part (2), is interposed between theother two in order to ensure distraction of the interspinous space andmovability of the device in the three spatial planes.
 2. The systemaccording to claim 1, wherein the spinous anchoring parts (1, 3)possess, on the side opposite the spinous process, orifices (9) ofvarious shapes, or blocks, in which the intermediate part (2) fits byway of corresponding blocks (13) or orifices in order to ensuremovability of the system.
 3. The system according to claim 1, whereinthe intermediate part (2) that is intended to be interposed between thespinous anchoring parts (1, 3) has different shapes and heights and isequipped or not equipped with passthroughs or blocks, and is fabricatedwith different types of material, to facilitate movement between thevarious elements of the device.
 4. The system according to claim 1,wherein the intermediate part (2) has an elliptical shape that fits intoorifices of the same shape on the spinous anchoring parts (1, 3) inorder to provide multidirectional movement for the device.
 5. The systemaccording to claim 1, wherein the intermediate part (2) is equipped withcylindrical blocks (13) that fit into the corresponding orifices (9) ofthe spinous anchoring parts (1, 3).
 6. The system according to claim 1,wherein the spinous anchoring parts (1, 3) are equipped with cylindricalorifices (9) to receive the cylindrical blocks (13) of the intermediatepart (2), thus forming a rotationally movable device.
 7. The systemaccording to claim 1, wherein the spinous anchoring parts (1, 3) areequipped with oblong orifices (9) to receive the cylindrical blocks (13)of the intermediate part (2), thus forming a device that is movablerotationally and in laterally sliding fashion.
 8. The system accordingto claim 1, wherein the intermediate part (2) is equipped with athreaded anterior orifice (18) to facilitate grasping and assembly, andhas transverse tunnels (15, 16) passing through that allow fastening ofthe system by way of a flexible ligamentary device and provide anadditional contribution to the shock-absorbing effect.
 9. The systemaccording to claim 1, wherein the intermediate part (2) is constitutedby a planar segment to allow rotation and anterior-posterior and lateraltranslation, and a spherical segment (19) to permit anterior, posterior,and lateral tilting, the entire assembly permitting movability in thethree spatial planes.